661560073 has 2 divisors, whose sum is σ = 661560074. Its totient is φ = 661560072.

The previous prime is 661560071. The next prime is 661560103. The reversal of 661560073 is 370065166.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 409131529 + 252428544 = 20227^2 + 15888^2 .

It is a cyclic number.

It is not a de Polignac number, because 661560073 - 2¹ = 661560071 is a prime.

Together with 661560071, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (661560071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330780036 + 330780037.

It is an arithmetic number, because the mean of its divisors is an integer number (330780037).

Almost surely, 2^661560073 is an apocalyptic number.

It is an amenable number.

661560073 is a deficient number, since it is larger than the sum of its proper divisors (1).

661560073 is an equidigital number, since it uses as much as digits as its factorization.

661560073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 22680, while the sum is 34.

The square root of 661560073 is about 25720.8101155465. The cubic root of 661560073 is about 871.3442349871.

The spelling of 661560073 in words is "six hundred sixty-one million, five hundred sixty thousand, seventy-three".